1. Field of the Invention
The invention relates to an inductive device, more particularly to an inductive module.
2. Description of the Related Art
A conventional inductive device, such as an inductor, a transformer, etc., is composed of one or more windings wound around a core that is made from a ferromagnetic material. Electromagnetic effects occur between the winding and the core when electric current flows through the winding. For producing larger transformers, a specialized coil winding machine is used for winding the windings onto the core, where production of the transformers is relatively automated. However, for smaller transformers, especially pulse transformers for use in the field of digital communication, to wind the windings, usually in the form of enamel-covered wires, on relatively small annular cores, and to place the winding-wounded core into a housing for subsequent packaging are steps that still require manual labor. Such manual operations have the following shortcomings:
1. Time-Consuming/Low Production Rate:
Due to the small size of the core, the enamel-covered wires need to be precisely wound around the core by operating personnel in a production line. However, the manufacturing process is time-consuming and costly in view of high labor expenses. in addition, since automation of the manufacturing process is not possible, low productivity results.
2. Low Yield:
Since pulse transformers of different standards require different numbers of windings, operating personnel must be aware of the number of windings required for the particular product currently being manufactured. Quality and accuracy of the products produced by a manufacturing process relying so highly on human operation are easily affected by human errors, thereby increasing deviations of the actual product from ideal specifications. Furthermore, enamel-covered wires are easily damaged during the winding and packaging operations.
In view of the above shortcomings, improvements are required in the overall structure, the manufacturing process, and productivity of relatively small inductive devices.
U.S. Pat. No. 7,253,711 discloses a method for making an embedded toroidal inductor that includes forming in a ceramic substrate conductive vias and conductive traces that define a three dimensional toroidal coil. The inductor disclosed in the patent has a ceramic core rather than a ferromagnetic core. In addition, the method requires the incorporation of low temperature co-fired ceramic (LTCC) technology, which is normally carried out under a temperature of between 900 to 1000 degrees Celsius, and which is relatively costly.